The present invention relates to a wheel bearing unit for motor vehicles particularly to the hub thereof and more particularly to shaping of the hub to clamp on a bearing.
A wheel bearing for motor vehicles is disclosed for example in Federal Republic of Germany OS 39 20 299. That wheel bearing requires the material of the inner ring of the bearing, which is provided with a bead, to have two contrary properties. The material must be capable of being hardened to obtain its bearing property and be plastically deformable to permit attachment. This requires an expensive heat treatment process, for example, case hardening. The same disadvantage also applies to a bearing disclosed in EP-OS 0 475 792 in which the bead is produced by expensive thermoforming.
In addition, if the bearing rings are developed as separate parts (as in FIG. 6 of EP-OS 0 475 792), there can be a problem that the geometry of the bearing rings can be affected by the shape of the bead with the result that the hub can be damaged. Therefore, the bearing rings must be provided with an initial stress which is sufficient but not too high.